Application services can be customized with authentication or provider logic through the event-driven application model of ASP.NET 3.5. The Authenticating and CreatingCookie events are both fired by the System.Web.ApplicationServices.AuthenticationService class. These events can be handled through the global.asax ASP.NET file, which creates the server-side application object. By handling the Authenticating event as shown in Example 6-16, you can provide custom authentication logic by using either a username/password combination or a custom authentication string that can be passed from the client and represent any string-serialized data from the user’s input. In addition to custom authentication logic, you can also choose a new provider based on the login name.
Example 6-16. The Authenticating event can be handled to provide custom authentication (Web/Global.asax).
void Application_Start(object sender, EventArgs e)
{
// Code that runs on application startup
System.Web.ApplicationServices.AuthenticationService.Authenticating +=
new EventHandler<System.Web.ApplicationServices.AuthenticatingEventArgs>
(AuthenticationService_Authenticating);
}
void AuthenticationService_Authenticating(object sender, System.Web.
ApplicationServices.AuthenticatingEventArgs e)
{
string username = String.Empty;
string password = String.Empty;
// You could pass in custom credentials
string[] credentials;
if(e.CustomCredential != null)
credentials = e.CustomCredential.Split(new char[] { ',' });
try
{
e.Authenticated = Membership.ValidateUser(e.UserName, e.Password);
}
catch
{
e.Authenticated = false;
}
e.AuthenticationIsComplete = true;
}The profile service also fires events that you can handle to provide custom validation. To perform data validation on the server before data is saved, handle the ValidatingProperties event. Example 6-17 demonstrates custom profile validation using this event.
Example 6-17. The ValidatingProperties event can be handled to provide custom server-side validation (Web/ Global.asax).
void Application_Start(object sender, EventArgs e)
{
// Code that runs on application startup
System.Web.ApplicationServices.AuthenticationService.Authenticating +=
new EventHandler<System.Web.ApplicationServices.AuthenticatingEventArgs>
(AuthenticationService_Authenticating);
System.Web.ApplicationServices.ProfileService.ValidatingProperties +=
new EventHandler<
System.Web.ApplicationServices.ValidatingPropertiesEventArgs>(
ProfileService_ValidatingProperties);
}
void ProfileService_ValidatingProperties(object sender,
System.Web.ApplicationServices.ValidatingPropertiesEventArgs e)
{
if (String.IsNullOrEmpty((string)e.Properties["startTopic"])
|| ((string)e.Properties["startTopic"]).Contains(@"") )
{
e.FailedProperties.Add("startTopic");
}
}Just as the authentication and profile services expose events to customize the service implementation, the role service can be configured using the SelectingProvider event. Example 6-18 demonstrates a customization that uses EmployeesRoleProvider for all Fabrikam employees and the default AspNetProvider for all other cases.
Example 6-18. The SelectingProvider event of the role service can be used to return alternative role providers (Web/Global.asax).
void Application_Start(object sender, EventArgs e)
{
// Code that runs on application startup
System.Web.ApplicationServices.AuthenticationService.Authenticating +=
new EventHandler<System.Web.ApplicationServices.AuthenticatingEventArgs>
(AuthenticationService_Authenticating);
System.Web.ApplicationServices.ProfileService.ValidatingProperties +=
new EventHandler<
System.Web.ApplicationServices.ValidatingPropertiesEventArgs>(
ProfileService_ValidatingProperties);
System.Web.ApplicationServices.RoleService.SelectingProvider +=
newEventHandler<
System.Web.ApplicationServices.SelectingProviderEventArgs>(
RoleService_SelectingProvider);
}
void RoleService_SelectingProvider(object sender,
System.Web.ApplicationServices.SelectingProviderEventArgs e)
{
if (e.User.Identity.Name.IndexOf("@fabrikam.com") > 0)
{
e.ProviderName = "EmployeeRoleProvider";
}
else
{
e.ProviderName = "AspNetProvider";
}
}